Devices and systems for gastric volume control

ABSTRACT

A gastric balloon includes a scaffold structure, one or more internal inflatable compartments within the scaffold structure, and one or more inflatable bladders formed over the space-filling compartment. The gastric balloon may be deployed transesophageally using a gastroscope and is inflated in situ, preferably using a combination of liquid and gas inflation media.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application claims the benefit under 35 USC § 119(e) ofprior provisional application No. 60/629,800 (Attorney Docket No.02209-000210US), filed on Nov. 19, 2004; and of prior provisionalapplication No. 60/567,873 (Attorney Docket No. 022209-000200US), filedon May 3, 2004, the full disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical apparatus andmethods. More particularly, the present invention relates to theconstruction and use of gastric balloons for treating obesity.

Obesity is a serious medical condition and has become a widespreadproblem in the United States and many other industrialized countries.While many obese patients may be treated by modifications to diet andexercise, a number of morbidly obese patients are resistant to treatmentand are candidates for surgical intervention. One surgical approach fortreating morbid obesity is referred to as gastric or jejunoileal bypasswhere a major portion of the gastro-intestinal tract is surgicallybypassed. While effective in some patients, gastric bypass procedurescan have significant undesirable side affects. Moreover, the initialsurgical procedure presents risks associated with open surgery. Thereare restrictive surgical procedures but they are less effective andstill invasive. Consequently, an effective, non-invasive medicaltreatment with lower risks and minimal side effects is needed for manymorbidly obese patients, who cannot tolerate surgical intervention, andmost premorbidly obese patients, who have no effective treatment becausetheir condition is not sufficiently severe to qualify them as surgicalcandidates.

As an alternative to such surgical procedures, the introduction ofspace-occupying structures into the stomach, often referred to as“gastric balloons,” has been proposed. Such gastric balloons may beintroduced through the esophagus and inflated in situ in order to occupya significant volume within the stomach.

Although found to be effective in some cases, the use of gastricballoons has been compromised by a number of deficiencies. The mostserious is a sudden or slow deflation of the gastric balloon that canallow the balloon to pass the pyloric valve and enter the intestines.Such unintentional passage of the deflated balloon into the intestinescan cause intestinal obstruction and be life-threatening. Consequently,gastric balloons currently marketed outside the US are generallyindicated for use of only up to six months.

The risk of deflation is exacerbated by the fact that the patient maynot immediately be aware that the balloon has deflated, delaying thepatient from seeing a physician. Thus, it would be desirable to provideapproaches to allow a patient to detect leakage or impending leakage.Currently to detect leakage, some practitioners add methylene blue dyeto the filling fluid, usually saline, prior to inflation. If themethylene blue leaks into the stomach, a blue color will be present inthe patient's excrement. This procedure has a number of deficiencies asevidenced by the continued reports of significant rates of intestinalobstruction and excretion of deflated balloons in clinical practice.Slow and intermittent leaks can release such small amounts of dye thatthe dye is not detectable in the excrement. Faults on the medicalprofessionals' part include mixing concentrations that makes detectionunreliable or simply forgetting to mix in the substance prior toinflating the balloon. On the patients' side, many have difficultiesdetecting slight changes in the color of the excrement, forget to checkdiligently, or simply find the task psychologically too unpleasant toperform.

Other problems include infections resulting from bacterial colonizationof the gastric balloon and lack of adequate sizing of the balloon priorto deployment in a patient's stomach. Additionally, most gastricballoons have been filled with saline or other liquid, making them heavyand uncomfortable within a patient's stomach. The weight of the balloonscan cause them to induce gastric hypertrophy and create gastricerosions, ulcers, lesions and abrasions within the stomach at the pointswhere they naturally rest.

For these reasons, it would be desirable to provide improved gastricballoon structures and methods for their use in treating obese patients.The balloons should be durable and the methods and apparatus willpreferably be comfortable to the patient and in particular should avoidsettling as a heavy weight in the patient's stomach. The gastricballoons and methods for their use should further prevent passage of anaccidentally deflated balloon across the pyloric valve and into theintestines, even when the balloon structure is compromised and theballoon looses inflation medium. It would be further desirable if adeflation or impending deflation of the balloon were detectable to thepatient in a rapid and reliable fashion. Such a detection system shouldalert the patient of failure and allow the patient to seek medical helpbefore the balloon has deflated to a size that could pass the pylorus.The compromised device could be then removed or replaced on a timelybasis. Additionally, it would be beneficial if the balloons wereresistant to bacterial and other microbial growth, thus lessening therisk of infection upon long-term deployment. Other improvements wouldinclude balloons and methods for their deployment which allow for propersizing the balloon and/or trimming or adjusting the balloon size evenafter deployment. At least some of these objectives will be met by theinventions described below.

2. Description of the Background Art

Gastric balloons and methods for their use in treating obesity aredescribed in U.S. Pat. Nos. 6,746,460; 6,736,793; 6,733,512; 6,656,194;6,579,301; 6,454,785; 5,993,473; 5,259,399; 5,234,454; 5,084,061;4,908,011; 4,899,747; 4,739,758; 4,723,893; 4,694,827; 4,648,383;4,607,618; 4,501,264; 4,485,805; 4,416,267; 4,246,893; 4,133,315;3,055,371; and 3,046,988 and in the following publications: U.S.2004/0186503; U.S. 2004/0186502; U.S. 2004/0106899; U.S. 2004/0059289;U.S. 2003/0171768; U.S. 2002/0055757; WO 03/095015; WO88/00027;WO87/00034; WO83/02888; EP 0103481; EP0246999; GB2090747; and GB2139902.

BRIEF SUMMARY OF THE INVENTION

The present invention provides improved gastric balloons and methods fortheir deployment and use. The balloons will typically have an overallvolume or displacement selected to leave a residual volume in theproximal area of the stomach in the range from 10 ml to 100 ml, usuallyfrom 20 ml to 40 ml. As discussed in detail below in some embodiments,the volume will be adjustable to optimize treatment on individualpatients. The gastric balloons will typically be designed to conform tothe natural shape of the gastric cavity while maintaining the normalfunction of the stomach. The balloon will preferably have a crescent or“kidney” shape to align the balloon wall against the greater and lessercurvatures of the stomach, an oval cross section to conform to the shapeof the cavity in the sagittal plane, and delineate a space proximallyfor the collection of ingested food and another space distally foractive digestion.

The gastric balloons include at least two principal structuralcomponents. The first principal structural component is an expandablescaffold which helps define a shape conforming to a gastric cavity,typically a crescent or “kidney” shape, when expanded. The scaffold maybe self-expanding, e.g. formed from a shape memory metal or shape memorypolymer, or may be inflatable with an incompressible fluid, such assaline, water, oil, gel, or other liquid, gel, slurry, solution, or thelike. Use of an incompressible inflation or filling fluid helps rigidifythe scaffold so that it maintains its shape for extended periods whenimplanted in the stomach. The expanded shape and side of the scaffold byitself or together with an intact portion of the device form an objectthat is too large in all orientations, even when compressed inperistalsis, to permit the device to pass the pylorus.

The second principal structural component comprises one or moreinflatable or otherwise expandable space-occupying structures orcompartments which are secured to the interior and/or exterior of theexpandable scaffold. The space-filling structures or compartments assumea space-filling configuration when inflated or otherwise filled orexpanded, typically being inflated or filled at least partly with acompressible fluid, typically a gas such as air. Such filling orinflation of the scaffold and/or the space-filling compartment(s) willusually be accomplished from an external pressurized fluid source, butcertain gaseous inflation media can be generated in situ within thecomponent by chemical reactions induced by mixing reactants or otherwiseinitiating a gas-producing chemical reaction. In some cases, thescaffold may form all or a portion of the space-filling structure orcompartment.

The scaffold and the inflatable compartment(s) may be joined together ina number of different ways. Self-expanding scaffolds may be disposedinside of, within, or over the walls of the inflatable compartment(s).The scaffolds may have a number of different geometries, includingspines, hoops, serpentine elements, plates, shells, or the like. In oneparticular embodiment, a self-expanding scaffold comprises a singlespine which runs axially along one side of the inflatable compartment(s)with a number of generally oval rib structures extendingcircumferentially around the inflatable compartment(s). In anotherspecific example, the self-expanding scaffold may be in the form of aplurality of interleaved panels which form an umbrella-like cap on oneend of the scaffold, typically the end disposed adjacent to theesophagus after deployment. In still another example, the expandablescaffold may be an inflatable saddle or shell which is attached over anouter surface of one or more inflatable compartment(s). In still otherembodiments, the scaffold structure may be formed internally with two ormore inflatable compartments disposed on the outside of the structure.For example, in a particular embodiment, the scaffold is inflatable andforms an X-shaped cross section with four inflatable compartments, onein each quadrant of the X. Numerous other particular configurations maybe made within the principles of the present invention.

The gastric balloons of the present invention may comprise two or morewalls or layers or lamina of materials to improve the durability of thedevice by optimizing the performance characteristics of differentmaterials. This is desirable because the maximal thickness of the entiredevice in its deflated state such that it can be passed uneventfullythrough the esophagus is limited and is useful even for a simple, singlecompartment balloon. Typically, the outermost layer is made ofmaterials, such as silicone rubber, selected primarily for theirbiocompatibility in the stomach and resistance to an acidic environmentand the innermost layer is made of materials selected primarily fortheir resistance to structural fatigue and permeability to the fillingfluid. In addition, use of multiple layers allows the layers to beformed from different materials having different properties, to enhancethe performance characteristics of the entire balloon structure. Theinner layers could have biocompatibility of a shorter duration than theoutermost layer. It may be desirable to enhance the durability furtherby embedding other structural elements in the layers, such as a meshmade of metal, polymer, or high strength fibers, such as Kevlar®. In thesimplest embodiment, the two layers are either bonded together tofunction as a single wall or left unbonded such that the layers couldslide by each other except at certain attachment points.

Optionally, a variety of structural elements may reside in between theoutermost and innermost layers. For support, the mesh of high strengthfibers, polymer, or metal could constitute another layer in of itselfinstead of being embedded in the layers. Alternatively, the mesh formsor is a component of the expandable scaffold. One or more layers ofmaterials selected for the optimal balance of biocompatibility,impermeability, rigidity, durability among other criteria could be addedto enhance the structural performance characteristics of the devicefurther.

Optionally, a failure detection system may reside in between any of thelayers. This is desirable and useful even for a single compartmentballoon. An example of a chemical system is based on a thin film orcoating of a substance, such as a dye, that is released into the stomachin the event the integrity of the layer external to the substance iscompromised and detected upon excretion or regurgitation by the patient.Optionally, different substances may be placed in between differentlayers so that the particular layer which failed may be identified basedon what is detected. Optionally, the substance could be embedded in thelayer so that partial breach of the layer would result in the substancebe in contact with the stomach contents. Incorporating the substance(s)in the device eliminates a step for the medical professional to measureand mix the substance(s) into the inflation media. Many errors includingmixing ineffective concentrations such that detection becomesunreliable, contaminating the different components such thatidentification of the particular failed component becomes unreliable,confusing the substance(s) with its respective component, or simplyforgetting to mix in the substance(s) are prevented. Furthermore, thedetection mechanism is standardized for the device and easier formedical professionals other than the person deploying the device todiagnose any failure.

The inflatable compartment(s) may be inflated with compressible fluids(gases), incompressible fluids (liquids), or in some cases mixtures ofgases and liquids. When multiple inflatable compartments are used, eachcompartment may be inflated with the same or different gas(es),liquid(s), and/or mixtures thereof. The use of gas and liquid forgastric balloon inflation has a number of advantages. A principalbenefit is the ability to control buoyancy and weight distributionwithin the balloon, e.g., by filling most of the compartments with a gasand distributing the non-gas inflation medium in other compartmentsthroughout the balloon, the risk of concentrated pressure points againstthe stomach is reduced. Second, by properly controlling the ratio of airor other gas to saline or other liquid, the gastric balloon can beprovided with a desired buoyancy and mass within the stomach. Typically,the ratio of air: liquid can be in the range from 2:1 to 10:1, morepreferably within the range from 3:1 to 6:1. Such ratios can provideeffective densities relative to water at a specific gravity in the rangefrom 0.09 to 0.5, usually from 0.17 to 0.33, depending on the totalvolume occupied by the device. Typically, the weight of the filledballoon is in the range from 50 gm to 500 gm, usually being from 50 gmto 450 gm. The use of gastric balloons which are light and less densewill reduce the risk that the balloons will cause abrasion, pressureinduced lesions, shearing lesions, or other trauma when implanted in thestomach for extended periods of time.

Optionally, the gastric balloons of the present invention may furthercomprise at least one separately inflatable or otherwise expandableexternal bladder formed over an exterior surface of the balloon. Theexternal bladder(s) will be separately inflatable from both the scaffoldand the space-filling compartment(s) although they may be attached to orshare common walls with either or both of these other principalstructural components. The bladder will be positioned on the exterior ofthe balloon so that it can control either or both of the shape andbuoyancy of the balloon as a whole. Typically, the bladder will beinflated at least partly with a compressible gas, typically air or otherbiocompatible gas. Often, the balloon will be underfilled, i.e., filledwith a volume that does not distend or increase the wall tension beyondthat of the unfilled bladder.

The expandable scaffold, the inflatable space-filling compartment(s) orstructures, and optionally the inflatable bladder(s) may be joinedtogether in the overall gastric balloon structure in a variety of ways.Typically, each component may be separately formed and joined byadhesives, bonding, or by other non-penetrating fasteners, or by othermeans. Alternatively, all or a portion of these principal structuralcomponents may be formed by co-extrusion to provide the desiredinflatable volumes. Generally, however, it will be desirable to avoidpenetrating fasteners and/or stitching of the principal structuralcomponents since such penetrations can compromise the integrity of thecomponents and subject the balloon to leakage over time.

The expandable scaffold upon self-compression or inflation may defineone or more internal regions or volumes which receive the inflatablecompartment(s). In a first exemplary illustrated embodiment, thescaffold when inflated has a X-shaped cross-section which defines fouraxially aligned quadrants or channels which would allow relatively freepassage of food past the scaffold and through the stomach in the absenceof the inflated internal component(s). The inflatable scaffold willusually be formed from a non-distensible material so that it can befully and generally rigidly inflated by the liquid or otherincompressible fluid. The internal components, in contrast, may beformed from an elastic and/or inelastic material to permit its volume tobe differentially inflated and adjusted. Usually, the space-fillingcompartment(s) will leave at least a portion of the channels availablefor the passage of food, albeit in a restricted or modulated fashion.Alternatively, the shape and structure of the entire device could allowingested food to pass between the exterior and the stomach wall.

Alternatively, the scaffold could comprise a metal or polymeric scaffoldor other open structure which supports the other balloon components butwhich is not itself inflatable. For example, an open lattice formed froma shape memory material, such as a nickel-titanium alloy, can becompressed and constrained together with the inflatable components fordelivering to the stomach. The structure can be self-expanding, i.e.deployed by being released from constraint after delivery to the stomachso that the lattice opens to its memory shape. Such self-expandingscaffolds are preferably collapsible under restraint to a relativelylow-profile configuration, typically having a width no greater thanabout 30 mm, preferably no greater than about 20 mm, in order to permitdelivery through a gastroscope or other tubular introducer positionedthrough the esophagus. For example, the lattice could comprise orconsist of one or more axial members having hoop, loop, or rib elementsattached along their length(s). Alternatively, the lattice couldcomprise a plurality of interleaved panels which could be folded and/orrolled into a low width configuration. Other examples includecollapsible meshes, collapsible coils, malecot structures, and the like.In contrast, the inflatable components will be deflated to permitintroduction in a low profile configuration. The inflatable componentscan have a variety of geometries including X-shaped cores, inflatablesaddles, inflatable caps, and the like. The inflatable components can bedeployed by inflation as described elsewhere herein. Alternatively, insome instances, the scaffold might be an outer shell or “exo-skeleton,”in some cases simply being a non-distensible sheath or cover whichpermits inflation of two or more inflatable compartments therein. Stillfurther alternatively, the scaffold may be formed of a solid materialfor the attachment of the other components of the device in a particularconfiguration such that collectively, the components assume the desiredphysical shape or perform the desired functions.

The external bladder(s) may also be formed from elastic and/or inelasticmaterials, such as silicone rubber and polyethylene terephthalate film(Mylar®), respectively, so that they can be inflated at the end of theprocedure to properly position the gastric balloon within the stomachand to provide for proper sizing of the balloon within the stomach. Inan illustrated embodiment, the gastric balloon includes onespace-filling compartment and one external bladder for each of the fourchannels formed by the inflatable scaffold, but the number ofcompartments and/or bladders may differ from the number of channels.

Most embodiments of the present invention will include at least two ormore inflatable-space-filling compartments and in some cases may alsoinclude one or more inflatable external bladders. The inflation ofmultiple inflatable compartments and external bladders may beaccomplished in a variety of ways. Most simply, each inflatablecompartment and inflatable external bladder (if any) could be connectedto an independent inflation tube which can be disconnected afterinflation. The use of multiple independent inflation tubes allows eachinflatable compartment and external bladder to be selectively andindependently filled, further allowing filling at different pressures,with different inflation fluids, and the like. The use of multipleinflation tubes, however, is not generally preferred since the tubes,collectively, can have rather a large cross section, and such multipletubes may interfere with device deployment.

The multiple inflatable compartments and external bladders of thepresent invention may be filled through a single inflation tube in atleast two ways. First, by connecting the inflatable compartments andexternal bladders in series, for example using a series of one-wayvalves, inflation through a first inflatable compartment (or externalbladder) can sequentially fill additional compartments and bladders inthe series as the pressure in each compartment raises and in turn beginsto fill the next compartment or bladder in series. Such an approach,however, is generally less preferred since it does not permit selectivefilling of the compartments and therefore does not permit the pressureand/or composition of the inflation fluid to be controlled anddifferentiated between the multiple compartments.

Thus, a presently preferred structure and method for filling themultiple compartments and external bladders (if any) of the presentinvention is to use a selective valve system which can be accessed andcontrolled by a single inflation tube in order to independently andselectively inflate each of the inflatable compartments and externalbladders (if any). Such selective valving system may be constructed inany of at least several ways. For example, an inflation tube having alateral inflation port near its distal end can be disposed between two,three, or more one-way valves opening into respective inflatablecompartments and external bladders. By rotating the inflation tube, theinflation port on the tube can be aligned with one of the one-way valvesat a time, thus permitting inflation of the respective compartment orbladder to a desired pressure and with a desired inflation fluid,including liquid inflation fluids, gaseous inflation fluids, andmixtures thereof. The rotatable and selectable inflation tube could beremovable. Alternatively, at least a portion of the inflation tube couldbe permanently mounted within the gastric balloon structure, allowing anexternal portion of the inflation tube to be removably coupled to theinternal portion to deliver the inflation fluids.

In addition to rotatably selectable inflation tubes, the inflation tubecould be axially positionable to access linearly spaced-apart one-wayvalve structures, each of which is connected to a different inflatablecompartment or external bladder.

As a still further alternative, a single inflation tube could berotatably mounted and have several inflation ports along its lengths.Each of the inflation ports could be disposed near one, two, or moredifferent one-way valves communicating with different inflatablecompartments and/or external bladders.

In all these cases, the one-way valves will permit inflation byintroducing an inflation medium at a pressure sufficiently high to openthe one-way valve and permit flow into the associated inflatablecompartment or external bladder. Upon removing the pressurized inflationsource, the one-way valve will close and remain sealed in response tothe increased pressure within the inflatable compartment or externalbladder.

In all cases, the inflation tube(s) will be removable from the connectedcomponent after the component or multiple components have been inflated.Thus, as described in more detail below, the gastric balloon may bedelivered to the stomach in a deflated, low profile configuration,typically through a gastroscope or other transesophageal deliverydevice. Once in place, the expandable scaffold may be deployed and theinflatable components may be inflated, filled, or otherwise expanded insitu to a desired volume and buoyancy typically by delivering theinflation media through the inflation tubes.

Once the desired inflation size is reached, the inflation tubes may bedetached from each of the compartments allowing self-sealing so that theinflation medium remains contained for extended periods of time. Toensure the containment of the medium, valves may be placed in series forany one or more of the inflatable component(s) and/or bladder(s). Otherexpansion protocols are described elsewhere herein. In particular,component, compartment, or portion of the balloon may be inflated insitu by inducing a gas-generating reduction within the balloon. Thereactant(s) may be present in the balloon prior to introduction to thepatient or may be introduced using the connecting tubes afterintroduction to the stomach.

Although one illustrated embodiment of the present invention includesfour channels in the inflatable scaffold, it will be appreciated thatthe present invention will cover gastric balloon structures having onlya single passage or channel formed within the scaffold with a singlespace-filling compartment and single external bladder. Embodiments withtwo channels, space-filling compartments and external bladders as wellas three channels, three space-filling compartments, and three externalbladders, as well as even higher numbers will also be within the scopeof the present invention.

The dimensions of the scaffold, space-filling compartment(s) orstructure(s), external bladder(s), and/or isolated inflation chamberswithin any or all of these components, will be selected such that thecollective volume or physical dimensions of the chambers remaininginflated after deflation of any single chamber (or limited number ofchambers) is sufficient to prevent passage of the balloon through thepyloric valve. Usually, the volume(s) will be such that at least twoinflatable components and/or chambers within said components coulddeflate without risk of the “diminished” balloon passing through thepyloric valve, preferably at least three could deflate, and often atleast four or more chambers could deflate. The precise volume(s)necessary to prevent passage of the partially deflated balloon structurethrough the pyloric valve and may vary from individual to individual. Apreferred remaining residual inflated volume will be at least about 75ml, preferably at least about 100 ml and still more preferably at leastabout 200 ml. After partial deflation, the balloon should have adimension along any axis or its cross axis of at least 2 cm, preferablyat least 4 cm, and most preferably at least 5 cm.

Should any of the principal structural components or any portion(s)thereof fail, then the present invention optionally provides for failuredetection. This is desirable and useful even for a single compartmentballoon. For example, a substance may be disposed within any or all (atleast one) of the internal volumes of the inflatable scaffold, theinflatable space-occupying component(s), and/or the external bladder (orany chambers therein), where the substance is detectable upon releaseand excretion or regurgitation by the patient. For example, thesubstance may be a dye, a scented composition, a benign symptom-inducingagent such as polyvinyl pyrolidine (PVP), or the like. The substancewill usually be disposed within each of the inflatable volumes of thescaffold, space-occupying compartment, and the external bladder so thatfailure of any single component or chamber thereof will be provided.Optionally, different substances may be placed in different componentsso that the particular component which failed may be identified based onwhat is detected. The substance may be detectable directly by sight,smell, or sensation, and/or by reaction with water in the toiletoptionally with the addition of a detection reagent.

A particular failure detection system according to the present inventionfor gastric balloons comprises a chemical and a chemical vapor detector.Optionally, the system includes at least one other chemical orbiochemical that reacts with the chemical, its metabolite, or itsreaction product. While this invention is described being used inconjunction with a gastric balloon, it does not exclude use in otherbiomedical devices where signaling a potential failure or malfunction,especially those potentially leading to a catastrophic loss, is desired.The chemical is disposed in a structural component or in an enclosedvolume of the device but released into the body upon a breach in theintegrity of the device. After release, the chemical, either in itsstable form, metabolite, or reaction product is eventually secreted orexcreted into the bodily fluids or exhaled gases. The chemical, itsmetabolite, or reaction product is sufficiently volatile in its secretedor excreted form so that the vapor concentration is significant enoughto be detected by a sensor. Optionally, the system could be improved bysubjecting the chemical, its metabolite, or reaction product to certainphysical perturbation, such as heat or sonic waves, such that the vaporconcentration is altered. Alternatively, the system could be improvedthrough a reaction where the chemical, its metabolite, or reactionproduct is mixed with other chemicals or biochemicals, includingsolvents, resulting in a product whose vapor concentration has changedenough to be detected by a sensor. Once the sensor is triggered, asignal indicating the compromised state of the device is sent in orderto seek medical assistance on a timely basis. The system requiresminimal motivation and judgment in diagnosis and enables detectingdevice failure in a more consistent and reliable fashion at home. Thetask of checking one's excrement is thereby avoided.

The chemical could be naturally occurring, synthetic, or made by thehuman body. Preferably, it is biocompatible to the human body at theconcentration that would result if the amount disposed in the device isreleased completely in one event. Upon such an event, for example, atear or break in a component, the chemical is released into directcontact with the contents of the body cavity, surrounding tissues ortheir secretions. It is then absorbed and secreted or excreted in thebody fluids or exhaled gases in its stable form. Alternatively, thechemical is metabolized by the body and its metabolites are secreted orexcreted in the body fluids. Alternatively, the chemical or itsmetabolites react with the contents of the body cavity, surroundingtissues or their secretions, or any part of the body until the reactantproducts are secreted or excreted. The change in vapor concentration ofthe chemical, its metabolites, and/or reactant products is then detectedby the sensor.

Alternatively, more than one chemical could be disposed separately ortogether as a mixture in the device. After release, the chemicals arethen absorbed and secreted or excreted in the body fluids or exhaledgases in their stable forms. Alternatively, at least one of thechemicals is metabolized by the body and its metabolites are secreted orexcreted in the body fluids or exhaled gases and the others could have aseparate functions, such as a stabilizing agent or catalyst.Alternatively, at least one of the chemicals reacts with the contents ofthe body cavity, surrounding tissues or their secretions or any part ofthe body until the ultimate reactant products are secreted or excreted.Alternatively, at least one of the chemicals or its metabolites orreactant products react with each other in the presence of the contentsof the body cavity, surrounding tissues or their secretions or any partof the body until the ultimate reactant products are secreted orexcreted. At least one of the products of the reaction is then secretedor excreted in its stable form or as metabolites in the body fluids orexhaled gases. Used as a mixture, the change in vapor concentration ofone or more of the chemicals, their metabolites, or their reactionproducts could be more readily detected to increase sensitivity of thedetection system or the change in vapor concentration of more than oneincreases the specificity.

Optionally, more than one chemical or more than one mixture of chemicalsmay be disposed in different parts or components in the device so thatmore than one part or component which has been compromised may beidentified based on which chemical was detected.

Optionally, more than one chemical or more than one mixture of chemicalsmay be disposed in the same part or component in the device so that thedegree of compromise may be determined based on which chemical or acombination of chemicals was detected.

The chemical or mixture of chemicals can be disposed anywhere in thedevice or its components but typically in the wall of the balloon or anypart that is more likely to be compromised. It can be distributed evenlythroughout the structure or in an irregular fashion but preferablywidely enough to cover the potential sites of failure. The preferredconfiguration is a fine lattice or continuous film of the chemical orchemical mixture embedded in the wall or in between layers of the wallcovering the entire balloon, thereby conforming to the shape of theballoon. Such a configuration optimizes the performance of the system indetecting failures early. As the site of the breach cannot be predicted,a breach is unlikely to be missed by covering the entire balloon.Compromise of the balloon typically starts with a somewhat linear splitor tear in surface of the balloon wall from mechanical fatigue. As thesplit propagates, it will soon expose more and more lines of the latticeor area of the film to the stomach contents. Consequently, as the sizeand seriousness of the breach increases, the more the chemical isreleased and the probability of detection increases. Being embedded inthe wall of the balloon further enables detection before a full breachof the entire thickness of the balloon wall.

Optionally, the performance could be enhanced by subjecting thechemical, its metabolite, or reactant product to certain physicalperturbation, such as heat or sonic waves, such that the vaporconcentration is altered. For example, the vapor concentration could beincreased in a well heated room or by a toilet flush. Alternatively, thesystem could be enabled through a reaction where the chemical, itsmetabolite, or reactant product is mixed with other chemicals orbiochemicals (which need not be biocompatible) introduced exogenouslyand the vapor concentration of the exogenous reaction product isdetected by the sensor. For example, a supply of the exogenous chemicalcan be packaged like a solid toilet bowl cleaner and placed in the watertank. The chemical is dispensed consistently and reliably as a reactantinto the bowl. The reaction product in the resulting concentration is ata level necessary for detection but could be bioincompatible had thereaction occurred in the body.

The chemical vapor detector is based on either the natural olfactorysense or the commercially available technology of so-called “electronicnose”, with which certain chemicals can be detected at levels from partsper million to parts per billion. The detector is preferably powered bybatteries and portable enough to be worn on a wristband or belt or canbe placed conveniently near the toilet. Upon sensing the chemical, itsmetabolite, or the reaction product, the detector will alert the patientto seek medical assistance or alert medical professionals directlythrough other devices, such as Bluetooth linked to an autodialtelephone. The alarm could be auditory, such as beeping sounds, visual,such as flashing LED's or a LCD display, sensory, such as vibrations, orpreferably a combination of any or all of the above. Optionally, thedetector could have different auditory, visual, sensory, or differentcombinations to identify the source of the detected breach, especiallywith more than one chemical is used. For example, LED's of differentcolors or different sounds could be used. The alarm could furtherindicate the seriousness of the breach. For example, when multipleprobes detect a breach, the volume of the alarm would increase to ahigher level.

The present invention further provides a wireless failure detectionsystem for gastric balloons and methods for their deployment and use.While this invention is described being used in conjunction with agastric balloon, it does not exclude use in other biomedical deviceswhere signaling a potential failure or malfunction, especially thosepotentially leading to a catastrophic loss, is desired. The failuredetection system comprises two probes, a wireless transmitter, and awireless detector. While this invention is described using radiofrequency as the signal transmission of choice, it does not excludeother carrier waves, such as light or acoustic, or via physicalproperties, such as magnetism or temperature. The probes are connectedelectronically to the wireless transmitter, which can emit a signalrecognized by the detector. Upon direct contact with the stomachcontents by the probes, the transmitter is enabled to signal thedetector to notify the patient that the integrity of the balloon iscompromised and, therefore, seek medical assistance. The system requiresminimal motivation and judgment in diagnosis and enables detectingdevice failure in a more consistent and reliable fashion at home. Thetask of checking one's excrement is thereby avoided. The system can bedesigned to function in a variety of algorithms to notify the patient ina simple, unequivocal fashion. For example, in a toggle algorithm, thetransmitter is either on in the static state or preferably off in orderto reduce the need for power. Upon direct contact with the stomachcontents, the probe causes the transmitter to turn the signal off orpreferably on to be able to send a wireless signal on a continuousbasis. The wireless signal or lack thereof is recognized by the detectorto notify the patient that the integrity of the balloon is compromised.

Alternatively, the algorithm could be based on time, amplitude,frequency, or some other parameter. For example, the transmitter maysend a wireless signal at a predetermined time interval in its staticstate. The detector recognizes the length of the interval as normal andthe existence of the signal as the system in working order. Upon directcontact with the stomach contents by the probes, the transmitter isenabled to send the same signal at different time intervals or adifferent signal, which is recognized by the detector to notify thepatient that the integrity of the balloon is compromised. The lack of asignal is recognized by the detector to notify the patient of adetection system malfunction and potential compromise of the integrityof the balloon.

Optionally, more than one probe or more than one type of probe may beplaced internally in different parts or components in the device so thatthe particular part or component which failed may be identified based onwhich probe was activated. The transmitter would send different signalsfor the receiver to display the source of the failure.

The internal probe could be of any shape and is disposed in the interioror preferably in the wall of the balloon. The preferred configuration isa fine lattice or continuous film of the detection material embedded inthe wall or in between layers of the wall covering the entire balloon,thereby conforming to the shape of the balloon. Such a configurationoptimizes the performance of the system in detecting failures early. Asthe site of the breach cannot be predicted, the probe would be unlikelyto miss detecting the breach by covering the entire balloon. Compromiseof the balloon typically starts with a somewhat linear split or tear insurface of the balloon wall from mechanical fatigue. As the splitpropagates, it will soon expose more and more lines of the lattice orarea of the film to the stomach contents. Consequently, as the size andseriousness of the breach increases, the probability of detectionincreases. Being embedded in the wall of the balloon further enablesdetection before a full breach of the entire thickness of the balloonwall. There are further advantages. As the size of the balloon that canpass uneventfully through the esophagus is limited, typically no largerthan 2 cm in diameter in its deflated cylindrical shape, the volume ofdetection material per area of balloon wall is reduced. Furthermore, thelattice or film could provide additional structural support to thedevice.

The detection material could be any metal, polymer, fiber, orcombination thereof, with or without any coating that can generate anelectrical charge or enable flow of electric current when in contactwith the stomach contents. For example, an electrical charge could begenerated from a non-toxic chemical reaction when the lattice exposedunderneath a tear comes in contact with the acidic contents. Flow ofelectric current could be enabled when two ends of an electric circuitare in contact with electrolytes in the stomach. For example, a chargedlattice is embedded in the wall and the ground is the external probe onthe surface of the balloon or the lattice is ground and the probe ischarged. When the lattice is exposed to the electrolytes in the stomachcontent, the circuit is closed. Alternatively, the lattice and groundcould be separate from each other but interlaced in the wall of thedevice. Preferred materials include non-corrosive, biocompatible metalsand elastomers containing electrically conductive particles.

The transmitter can be a simple wireless signal generator triggered byan electric current or preferably a transponder using thewell-established RFID technology, i.e., produces a wireless signal whentriggered by an interrogating signal. The electric charge generated orthe electric current enabled by the probe in contact with the stomachcontents enables the transmitter to emit or causes it to emit a wirelesssignal. Typically, the transponder is powered by the interrogating radiofrequency signal so that no power source of its own is required.Alternatively, the transmitter could be powered by a micro battery or bythe electrical power generated by a chemical reaction. For protectionfrom degradation by an acidic and electrolyte solution and becomepotentially toxic, the transmitter or transponder circuit is encased ina highly resistant material, such as silicon rubber or stainless steel.The transmitter or transponder circuit can be placed on the exterior,embedded in the wall, or preferably in the interior of the balloon forfurther shielding from chemical degradation and mechanical stress. Itcan be placed in any orientation, preferably in the plane where theantenna is most sensitive and the transmitter is most effective insending and receiving signals through body tissue.

The wireless signal from the transmitter is recognized by a detectorexternal to the body. The detector could be simply a receiver tuned tothe transmitter's signal or, preferably, a combination of both atransmitter of a signal to interrogate the transponder and a receiver todistinguish the different signals from the transponder. The detector ispreferably powered by batteries and portable enough to be worn on awristband or belt or can be placed conveniently near a place where thepatient spends most of his time. Upon receiving a signal that a breachhas occurred, the detector will alert the patient to seek medicalassistance or alert medical professionals directly through otherdevices, such as Bluetooth linked to an autodial telephone. The alarmcould be auditory, such as beeping sounds, visual, such as flashingLED's or a LCD display, sensory, such as vibrations, or preferably acombination of any or all of the above.

Optionally, the detector could have different auditory, visual, sensory,or different combinations to identify the source of the detected breach,especially with more than one probe or more than one type of probe. Forexample, LED's of different colors or different sounds could be used.The alarm could further indicate the seriousness of the breach. Forexample, when multiple probes detect a breach, the volume of the alarmwould increase to a higher level.

As a further option, at least a portion of the exterior of theinflatable balloon will be coated or impregnated with an anti-microbialand/or adhesion resistant agent. Preferably, the entire exposed surfaceof all components of the balloon will be so coated or impregnated toinhibit colonization of the balloon by bacteria or other microbes,and/or reduce possible accumulation of food particles on the device.Suitable anti-microbial agents include polyethylenetetrafluoride (PTFE),and antibiotics.

The present invention further provides methods for treating obesity in apatient. The methods comprise introducing a gastric balloon structure tothe patient's stomach. An inflatable scaffold which forms part of theballoon is then filled with an incompressible fluid to provide a fixedsupport geometry. At least a portion of a separate space-fillingcompartment is then filled at least partly with a compressible fluid,typically a gas such as air, nitrogen, or the like, within the remainder(if any) being filled with an incompressible material, such as a liquid,gel, slurry, or the like. In this way, the buoyancy of the balloon maybe controlled within the limits described above.

The methods of the present invention will usually further comprisedetermining the size of the gastric cavity and selecting a gastricballoon of proper size prior to introducing the balloon to the stomach.Such size determination may comprise visually examining the gastriccavity, typically under direct observation using a gastroscope, butalternatively using fluoroscopy, ultrasound, x-ray or CAT scanning, orany other available imaging method. An estimate of the dimensions of thestomach and the size of the device can be made by direct observation ofthe interior of the stomach immediately prior to deployment.Alternatively, the dimensions of the feeding stomach, which is generallylarger than the resting stomach, and the size of the device will bedetermined at an earlier session where the patient has consumed orswallowed a biocompatible filling medium, e.g., water, contrast medium,food, etc. A sufficient amount of filling medium will be consumed sothat the imaging technique can detect full relaxation of the stomachduring feeding and estimate its dimensions and size.

Introducing may then comprise passing the gastric balloon in a deflatedconfiguration into the stomach through the same gastroscope.Alternatively, the deflated balloon could be introduced into the gastriccavity via an attachment to an orogastric or nasogastric tube. Theballoon will be oriented so that the scaffold will open with curvedgeometry conforming to the curve of the gastric cavity. Typically, thescaffold will be released from constraint to self-expand or will befilled through a removable inflation tube attached to the scaffold,where the inflation tube may be removed after filling. The scaffold willthen be sealed or will more typically be self-sealing upon detachment ofthe filling tube(s) to prevent loss of the inflating liquid medium.Similarly, the space-filling compartment(s) will also typically befilled through one or more inflation tube(s) removably attached to thecompartment(s), where the tube(s) are removed after the compartment(s)have been filled with the desired medium, typically a mixture of liquidand gas sources. Further, the external bladder(s) will typically befilled through one or more inflation tube(s) generally as describedabove for both the scaffold and the space-filling compartment(s).

After all the principal structural components of the gastric balloonhave been inflated or otherwise expanded and the associated inflationtubes released, any other anchors or tethers attached to the balloon mayalso be released, leaving the balloon free to “float” within thepatient's stomach. By properly selecting the ratio of liquid inflationmedium to gas inflation medium, as discussed above, the weight,distribution, and the buoyancy of the gastric balloon will be such thatthe balloon rests within the stomach without exerting undue pressure atany particular point, thus reducing the risk of abrasions or othertrauma to the stomach lining. The inflated gastric balloon may be leftin place for extended periods of time, typically as long as weeks,months, or even years.

After the balloon has been inflated and left in place, it may becomedesirable to adjust the size and/or buoyancy of the balloon for purposesof patient comfort, efficacy, or other reasons. To perform suchadjustments, the balloon will be transesophageally accessed, typicallyusing a gastroscope with suitable working tools introduced therethrough.For example, the balloon may be grasped with graspers and inflationtubes may be suitably attached or docked to inflation ports on theballoon structure. Typically, the inflation ports will all be locatednear the end of the gastric balloon structure which is oriented towardthe top of the stomach so that they are readily accessed through thegastroscope. After attachment with the inflation tube, the inflationmedium can be introduced and/or extracted, depending on whether theparticular structural component is to be enlarged, deflated, or have abuoyancy adjustment. Optionally, an incising instrument could beintroduced through the gastroscope to penetrate and deflate any filledcompartment to reduce the overall volume of the device and improveaccommodation of the device. Typically, these compartments are small toallow minor adjustments without jeopardizing the integrity of the deviceitself.

In addition to adjusting the size and/or buoyancy of the gastricballoon, it may become desirable or necessary to remove the ballooncompletely. To effect such removal, the balloon will again be accessedtransesophageally, typically using a gastroscope. The balloon will firstbe grasped or secured using a grasping tool. Then, one or more surfacesof the balloon may be penetrated or breached in order to release thecontents of the balloon into the stomach. The contents will bebiocompatible gasses or liquids so that release into the stomach willnot be a concern. After the contents of the compartments have beenreleased, the balloon may then be pulled through the patient'sesophagus, typically by pulling with the grasping tool. It may bepossible to pull the deflated gastric balloon through the workingchannel of the gastroscope, but more often the balloon will simply bewithdrawn through the esophagus as the gastroscope is withdrawn.Optionally, a sheath or other protective cover may be placed over thedeflated balloon in order to reduce the risk of trauma or injury to theesophagus upon withdrawal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a gastric balloon constructed in accordancewith the principles of the present invention, shown deployed in astomach.

FIG. 2 is a cross-sectional view taken along line 2-2 in FIG. 1.

FIG. 3 is a top view of the gastric balloon of FIG. 1, illustrating theinflation ports or nipples.

FIGS. 4A and 4B illustrate use of tools introduced through a gastroscopefor inflating and deflating the gastric balloon of FIG. 1, respectively.

FIGS. 5A through 5E illustrate a complete deployment protocol accordingto the methods of the present invention.

FIG. 6 is a frontal view of a gastric balloon with an optional materialincorporated in a lattice configuration in the wall of the deviceconstructed in accordance with the principles of the present invention.

FIGS. 7A through 7C are enlarged, peeled-back, cross-sectional views ofa portion of the multi-layered wall of the gastric balloon of FIG. 6constructed in different configurations in accordance with theprinciples of the present invention.

FIG. 8 is a magnified cross-sectional view with an element in a thinfilm configuration and in a lattice configuration in between layers ofmaterials used in construction of the balloon.

FIG. 9 is a frontal view of the portable detector with an example of afailure display and auditory alarm constructed in accordance with theprinciples of the present invention.

FIG. 10 illustrates an alternative balloon geometry in accordance withthe principles of the present invention, shown deployed in a stomach.

FIG. 11 illustrates first embodiment of a self-expanding scaffold forthe balloon geometry of FIG. 10.

FIG. 12 illustrates a second embodiment of a self-expanding scaffoldgeometry for a balloon having the geometry of FIG. 10.

FIG. 13 illustrates an inflatable scaffold suitable for use with aballoon having the geometry of FIG. 10.

FIG. 13A is a cross-sectional view taken along line 13A-13A of FIG. 13.

FIG. 14 illustrates a gastric balloon in accordance with the principlesof the present invention including a pair of inflatable space-fillingcompartments contained by an external sheath.

FIG. 15 illustrates a gastric balloon having two inflatablespace-filling compartments joined together by a spine structure.

FIGS. 16-18 are flow diagrams illustrating several valving systemssuitable for inflating gastric balloons having multiple inflatablecompartments and optionally internal bladders in accordance with theprinciples of the present invention.

FIG. 19 illustrates an exemplary structure for valving according to FIG.16.

FIGS. 20, 20A, and 20B illustrate an exemplary structure for valvingaccording to FIG. 18.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, a gastric balloon 10 constructed inaccordance with the principles of the present invention comprises aninflatable scaffold structure 12, four inflatable space-fillingcompartments 14, and four inflatable external bladders 16. Referring inparticular to FIG. 2, the inflatable scaffold 12 has a X-shapedcross-section and defines four generally axially oriented channels orquadrants, each of which receives one of the four inflatablespace-filling compartments 14. The four inflatable external bladders 16are mounted over the inflatable space-filling compartments 14, and theballoon 10 includes an upper cage 18 and lower cage structure 20 whichpermit grasping of the balloon using grasping tools, as will bedescribed in more detail below. In its deployed configuration, thegastric balloon 10 has a crescent or curved shape which conforms to theinterior shape of a gastric cavity, with the upper cage structure 18oriented toward the esophagus E, the lower cage structure 20 orientedtoward the pyloric valve PV.

Referring now to FIG. 3, the inflatable scaffold structure 12 isprovided with at least one inflation port or nipple 22 while theinflatable space-filling compartments 14 are provided with a separateport 24 and the inflatable external bladders are provided with aseparate inflation port 26. Although not illustrated, the scaffold,internal components, and external bladders could have isolated,inflatable volumes therein, each of which would be attached to aseparate inflation tube. By “subdividing” the volume of the variousprincipal structural components, the risk of accidental deflation of theballoon is further reduced.

As illustrated in 4A, after the gastric balloon 10 is introduced in itsdeflated configuration into the gastric cavity, the inflatablestructural components could be inflated using a single inflation tube 30introduced through the gastroscope G, or orogastrically ornasogastrically by itself or using an orogastric or nasogastric tube.Typically, the upper cage 18 will be held by a grasper 32 which canselectively hold and release the gastric balloon 12 during inflation andsubsequent deployment. Shown in FIG. 4A, inflation tube 30 can beselectively coupled to any one of the inflation ports 22, 24, or 26, andthe desired inflation medium introduced therethrough. Inflation tube 30will be suitable for delivering either liquid or gas inflation media,typically including saline, water, contrast medium, gels, slurries, air,nitrogen, and the like.

Usually, the inflatable scaffold structure 12 will be inflated entirelywith a liquid or other incompressible medium, such as a gel, slurry, orthe like. In contrast, the inflatable space-filling compartments 14 willat least partly be inflated with air or other gas. Often, however, theinflatable space-filling compartments will inflated with a mixture ofgas and liquid in order to control the buoyancy of the balloon 12.Finally, the external bladders 16 will typically be inflated with gas inorder to provide a relatively soft outer surface which can reduce traumaand abrasion.

The various structural compartments of the balloon may be made from thesame or different materials. Usually, the inflatable scaffold structure12 will be formed from a non-distensible (non-stretching) material sothat it may be inflated to become a relatively rigid structure.Alternatively, or additionally, the structures may be formed fromstiffer materials and/or be reinforced to increase the rigidity wheninflated.

In contrast, the inflatable space-filling compartments 14 and theinflatable bladders 16 may be formed in whole or in part from softerelastomeric materials in order to allow inflation flexibility, both interms of size and density of the combined inflation media. The elasticnature of the external bladders allows the peripheral dimensions of thegastric balloon to be adjusted over a significant range by merelycontrolling inflation volume. Elastic inflatable space-fillingcompartments can allow the amount of space occupied in the interior ofthe balloon to be adjusted, for example to adjust the amount of volumefilled by the balloons within the quadrants defined by the scaffoldstructure 12. Alternatively, the volume of incompressible fluidintroduced into non-elastic structures may be sufficient to control thevolume being occupied.

As an alternative to using a single inflation tube, each of theinflation ports 22, 24, and 26 could be pre-attached to separateinflation tubes. In such cases, after inflation of each structuralcomponent is completed, the necessary inflation tube could then bewithdrawn through the gastroscope G, leaving the gastric balloon 10 inplace.

Referring now to FIG. 4B, the balloon 10 can be deflated while graspingthe tip 18 of the balloon with grasper 32 through gastroscope G using ablade structure 40 introduced through the gastroscope. The bladestructure 40 will preferably be used to make one or more penetrations orbreaches within each of the inflatable components of the gastricballoon, including the inflatable scaffold, the inflatable space-fillingcompartment(s), and the inflatable external bladder(s)

Referring now to FIGS. 5A-5E, gastric balloon 10 is introduced to apatient's stomach S using a gastroscope G introduced through theesophagus E in a conventional manner. Standard procedures for preparingand introducing the gastroscope are employed, including checking forulcerations in the esophagus and performing further examination ifwarranted.

After introducing the gastroscope G, the size of the gastric cavitywithin stomach S can be estimated and a balloon of an appropriate sizeselected. The balloon 10 is then also introduced through the esophagus E(orogastrically or nasogastrically) using an appropriate catheter oroptionally using the inflation tube(s) which will be used to inflate theballoon. After the entire balloon is confirmed to be in the stomach at aproper orientation, typically using the gastroscope G, the variouscomponents of the balloon 10 may be inflated as shown in FIGS. 5C and5D. First, the inflation tube 32 attached to the port which is coupledto the scaffold 12 is inflated, typically using saline or otherincompressible liquid until the scaffold structure becomes relativelyrigid, as shown in FIG. 5C. During this inflation, the balloon 10 isheld by at least an inflation tube 32 and may optionally be held byadditional inflation tube(s) and/or a grasper 32.

After the scaffold 12 has been inflated, an additional syringe is usedto inflate the space-filling compartments through a second inflationtube 33, as shown in FIG. 5D. The space-filling compartments, again,will typically be inflated with a combination of saline or other liquidand air or other gas in order to achieve the desired density of theinflation medium therein. The external bladders 16 will be inflated in asimilar manner, typically using air or other gas inflation medium only.

When it is desired to remove the gastric balloon 10, the balloon may bedeflated as previously discussed and removed through the esophagus usinga grasper 32 passing through the gastroscope G, as shown in FIG. 5E.Typically, the balloon will be pulled out using both the gastroscope andthe grasper 32.

Referring now to FIG. 6, a gastric balloon 100 of a single compartmentconstructed in accordance with the principles of the present invention.As illustrated in FIG. 7A, the wall of the balloon comprises at theminimum an outermost layer 102 and innermost layer 104. The layers aremanufactured by either dipping a mold successively into solutions ofdifferent materials that dry and cure or preferably by successiveprecision injections of materials into a mold. Typically, the outermostlayer 102 is made of one or more materials, such as silicone rubber,selected primarily for their non-abrasiveness, biocompatibility in thestomach, and resistance to an acidic environment. Typically, theinnermost layer 104 is made of materials selected primarily for theirresistance to structural fatigue and impermeability to the fillingfluid. The inner layer 104 could have biocompatibility of a shorterduration than the outermost layer. The two layers are either bondedtogether to function as a single wall or left unbonded such that thelayers could slide by each other except at certain attachment points.

Referring now to FIG. 7B, it may be desirable to enhance the durabilityfurther by incorporating other structural elements in the layers, suchas a mesh 106 made of metal, polymer, or high strength fibers, such asKevlar, or the scaffold (not shown). The mesh could constitute aseparate layer as illustrated in FIG. 7B or instead, could be embeddedin one of the layers of material, as shown embedded in layer 104 in FIG.7C. A mesh 106 could inhibit the propagation of a tear in the layers.Many of these materials are radio-opaque which enables imaging clearlythe entire shape of the device using plain diagnostic X-ray radiography.

As illustrated in FIGS. 7B and 7C, in addition to layers of 102 and 106,one or more layers, 108 and 110, of materials selected for the optimalbalance of biocompatibility, impermeability, rigidity, shear resistanceamong other criteria could be added to enhance the structuralperformance characteristics of the device further.

Referring now to FIG. 7B, layers, 108 and 110, could also representother materials incorporated to enable or enhance certain functionalperformance characteristics of the device. Instead of disposing thedetection marker in the enclosed volume of the balloon, the marker mayreside in between any of the layers either in a thin film or in alattice configuration. It is also possible to dispose the marker in theopen spaces in the mesh (not shown). A thin film or coating of asubstance that is detectable upon excretion or regurgitation by thepatient, such as a dye, would be released into the stomach in the eventthe integrity of the layer external to the substance is compromised. Forexample, the substance that forms thin film is released into the stomachwhen a breach, such as a tear, occurs in layer 102.

Referring now to FIG. 7C, as an optional configuration, differentsubstances, 108 a and 108 b, may be placed in between different layersso that the particular layer which failed may be identified based onwhat is detected. For example, if 108 a were detected in the excrement,one would deduce that layer 102 has been breached but layer 110 has not.This would constitute a situation where medical assistance can beprovided on an elective basis. Once 108 b is detected in the excrement,one would deduce that at the minimum, layers 108 and 110 have both beencompromised leaving only layer 104 as possibly the last line of defense.This would represent a medical emergency where the device should beremoved before complete failure.

Another failure detection system comprises a chemical substance and achemical vapor detector, an “electronic nose,” that detects a change invapor concentration of the substance, its metabolite, or any of itsreaction products. Optionally, it includes at least one other chemicalor biochemical that reacts with the chemical, its metabolite, or any ofits reaction products to enhance the sensitivity and/or specificity ofdetection. When used in conjunction with a biomedical device, the systemrepresents a method to detect early potential failure or malfunctioninvolving a structural breach. While this invention is described beingused in conjunction with a gastric balloon, it does not exclude use inother biomedical devices where signaling a potential failure ormalfunction, especially those potentially leading to a catastrophicloss, is desired.

Referring again to FIG. 6, the gastric balloon 100 includes a chemicalsubstance in a lattice configuration 110 incorporated in the wall of theballoon. The chemical substance could be naturally occurring, synthetic,or made by the human body. As magnified in FIG. 8, the chemicalsubstance can be disposed in a fine lattice configuration 110 and/or ina thin film configuration 112 in the wall of the balloon in between twoor more layers, e.g., outermost layer 102 and innermost layer 104. Thechemical substance can be also disposed in any enclosed space in thedevice (not shown)

After the balloon 100 is deployed in the stomach, the chemical substancecomes in contact with and is released into the surrounding tissue andbody fluids upon a breach in the integrity of the wall. As illustratedin FIG. 8, the chemical substance 112 comes in contact with and isreleased when there is a tear in the outermost layer 102 of the balloonwall. After release, the chemical substance, either in its stable form,its metabolite, or reaction product is eventually secreted or excretedinto the bodily fluids. The chemical substance, its metabolite, orreaction product is sufficiently volatile in its secreted or excretedform so that the change in vapor concentration of the secreted orexcreted form is significant enough to be detected by a chemical vaporsensor. The chemical vapor detector is based on either the naturalolfactory sense or the commercially available technology of so-called“electronic nose”, with which certain chemicals can be detected atlevels from parts per million to parts per billion.

Referring now to FIG. 9, the sensor, power source, and electroniccircuit is enclosed within detector 120. The detector 120 is preferablypowered by batteries and portable enough to be worn on a wristband orbelt or can be placed conveniently near the toilet. Upon sensing thechemical substance, its metabolite, or a reaction product, the detectorwill alert the patient to seek medical assistance. The alarm could bevisual, such as lit or blinking LED's 122 and 124, and can designatedifferent levels of urgency depending on what was detected. For example,a lit LED 122 could indicate that chemical substance 112 in FIG. 8 hasbeen detected. It can be deduced that layer 102, external to 112 hasbeen breached. Since there are still more than two layers to breachbefore complete breach of the balloon wall, medical assistance can beprovided on an elective basis. In the same fashion, a lit LED 124, couldindicate chemical substance 110 has been detected, and therefore layer106 external to 110 has been breached. Since only layer 104 remains asthe last barrier to complete breach of the wall and when that occurscannot be predicted, the device needs to be removed on an emergentbasis. A power light 121 is provided to assure the device is on.

Shown in FIG. 9, the alarm 126 could also be auditory, such as beepingsounds, or sensory, such as vibrations, or preferably a combination ofany or all of the above. Optionally, the detector could have differentauditory, visual, sensory, or different combinations to identify thesource of the detected breach, especially with more than one chemicalsubstance used. The alarm could further indicate the seriousness of thebreach. For example, when breaches are detected, the volume of the alarmwould increase to a higher level.

Optionally, the system could be improved by subjecting the chemical, itsmetabolite, or reaction product to certain physical perturbation, suchas heat or sonic waves or a toilet flush, such that the vaporconcentration is altered. Alternatively, the system could be improvedthrough a reaction where the chemical substance, its metabolite, orreaction product is mixed with other chemicals or biochemicals,including solvents, resulting in a product whose vapor concentration haschanged enough to be readily detected by a sensor.

Optionally, detecting the change in vapor concentration of more than oneof the chemical substance, its metabolites, or its reaction productscould increase the sensitivity and/or specificity of the detectionsystem.

Another failure detection system comprises two electrical probes,wireless transmitter, and a wireless detector. While this invention isdescribed using radio frequency as the signal transmission of choice, itdoes not exclude other carrier waves, such as light or sonic, or viaphysical properties, such as magnetism or temperature. When used inconjunction with a biomedical device, the system represents a method todetect early potential failure or malfunction involving a structuralbreach. When used in conjunction with a biomedical device, the systemrepresents a method to detect early potential failure or malfunctioninvolving a structural breach. While this invention is described beingused in conjunction with a gastric balloon, it does not exclude use inother biomedical devices where signaling a potential failure ormalfunction, especially those potentially leading to a catastrophicloss, is desired.

Referring now to FIG. 6, the gastric balloon 100 includes two electricprobes. Probe 130 is on the external surface in contact with thesurrounding tissues, body fluids, and contents of the stomach. Thelattice configuration 10 provides the second probe incorporated in thewall of the balloon. The probe material could be any metal, polymer,fiber, or combination thereof, with or without any coating that cangenerate an electrical charge or enable flow of electric current when incontact with the stomach contents. The probes are connectedelectronically to the wireless transmitter 140, but are separated fromeach other by at least one layer of non-conductive material in theballoon wall. The transmitter can be a simple wireless signal generatortriggered by an electric current or preferably is a transponder usingthe well-established RFID technology, i.e., produces a wireless signalin response when triggered by an interrogating signal. In the intactstate, 130, 110, and 140 represent an open electrical circuit and thetransmitter is enabled to transmit a base signal.

As magnified in FIG. 8, the internal probe can be in a fine latticeconfiguration 110 or in a thin film configuration 112 in the wall of theballoon in between, at the minimum two layers, an outermost layer 102and innermost layer 104. The internal probe can be also disposed in anyenclosed space in the device (not shown). In the configuration describedin FIG. 8, probes 130 and 110 and transponder 140 represent one opencircuit and probes 130 and 112 and transponder 140 represent a secondopen circuit. Each open circuit enables the transponder to transmit abase signal.

After the balloon is deployed in the stomach, the external probe 130 isin contact with the surrounding tissue and body fluids and stomachcontents. Upon a breach in the integrity of the wall, such as a tear inthe outermost layer 102 as illustrated in FIG. 8, the leakage ofphysiologic fluid or stomach contents with electrolytes into the tearforms a salt bridge that closes the circuit formed probes 130 and 112and transponder 140. Once the circuit is closed, a toggle is switched inthe transponder, which will be enabled to transmit a “layer 102 breach”signal. Tears through layer 106 in the balloon wall will allow leakageof physiologic fluid or stomach contents with electrolytes into the tearforming a salt bridge that closes the circuit formed probes 130 and 110and transmitter 140. Closing this circuit switches another toggle in thetransponder, which will be enabled to transmit a “layer 106 breach”signal.

FIG. 10 illustrates an alternative crescent-shaped balloon geometrysuitable for use in the gastric balloons of the present invention.Gastric balloon 200 has a generally flat or truncated upper surface 202which is positioned adjacent to the esophagus E. A lower end 204 is alsogenerally flat or truncated. These flat ends 202 and 204 aredistinguishable from the more tapered ends of the prior gastric balloonembodiments. Although illustrated schematically as a single unit orstructure, it will be appreciated that the balloon 200 will usuallycomprise multiple independently inflatable space-filling compartmentsand optionally further comprise external inflatable bladders. Thegeometry shown in FIG. 10 is intended to illustrate the peripheral shapeof the device including all components.

Referring now to FIGS. 11-15, gastric balloon structures having thegeometry of balloon 200 in FIG. 10 may be deployed using a number ofdifferent expandable scaffolds. For example, as shown in FIG. 11, theballoon structure 200 may include an external “exo-skeleton” 210comprising a spine 212 and a plurality of ribs 214 extending laterallyfrom the spine. The spine 212 and ribs 214 are preferably made fromelastic components, such as nickel titanium alloys or other superelastic materials, permitting them to be folded and compressed to asmall width for introduction. The scaffold will then be deployed byreleasing the scaffold from constraint after it has been positionedwithin the stomach.

The balloon 200 may also be mated with an end cap 220. The end cap 220may include, for example, a plurality of interlaced panels which can befolded down to a low profile configuration for delivery. The panels maybe composed of elastic polymers, shape memory metals, shape memorypolymers, or the like. The use of end caps 220 is particularly usefulwhen the balloon will itself comprise a single compartment. The end capwill prevent accidental passage of the balloon through the pylorus evenupon rapid deflation of the balloon.

The balloon 200 may also be mated to an inflatable scaffold 230, whichmay be conveniently formed into the shape of a saddle, as shown in FIGS.13 and 13A. The balloon 200 may comprise one, two, or more separateinflatable compartments. Each of these compartments, as well as theinflatable scaffold 230, will require separate inflation, preferablyusing one of the valving mechanisms described hereinbelow. Theinflatable scaffold 230 could have other configurations as well, such asbeing in the form of a lattice with a central inflatable spine andmultiple arms disposed laterally outwardly about the remainder of theballoon 200.

Referring now to FIGS. 14 and 15, the balloon 200 may comprise first andsecond internal inflatable compartments 240 and 242 having an externalsheath or exoskeleton 244. The sheath 244 may be, for example, anon-distensible outer tubular structure having the desired crescentgeometry, with the inflatable compartments 240 and 242 disposed therein.Alternatively, the exoskeleton could comprise a mesh, fabric, or otherflexible containment member which holds the separate inflatablecompartments 240 and 242 in place relative to each other. At least aportion of the exoskeleton 244 could be made to be non-collapsible inorder to prevent accidental passage of the balloon through the pyloricvalve in case of unintended deflation of both of the inflatablecompartments 240 and 242.

The compartments 240 and 242 could also be held together by a spineelement 250, as shown in FIG. 15. The balloons would be attached to thespine, optionally by heat sealing or adhesives, usually one or morefasteners 252, such as adhesive straps, are provided about the peripheryof the inflatable compartments 240 and 242 to hold them together afterdeployment. The spine 250 can also optionally be used to receive anddeploy inflation tubes, as described in more detail below.

Each of the balloons 200 described above will be provided with a valvemechanism or assembly to permit selective inflation with liquid fluids,gaseous fluids, or a combination thereof. If only a single inflatablecompartment is utilized, the valving mechanism could be simply a one-wayvalve having a connector for releasably connecting to an inflation tube.For example, the inflation tube could be connected to the connector onthe valve prior to introduction of the balloon in the patient's stomach.After introduction, the inflation medium could be introduced through thetube, and the tube detached and removed after inflation is complete.Optionally, the inflation tube could be introduced later for reinflationof the balloon if desired.

When two or more inflatable compartments, and optionally externalbladders, are provided, the valve assemblies of the present inventionwill preferably provide for selectively delivering inflation medium toindividual inflation ports on each of the inflatable compartments,external bladders, and optionally inflatable scaffolds. Inflation valveswill usually comprise a one-way valve structure, such as a flap valve ora duckbill valve. The valves associated with each compartment will bearranged to permit manipulation of an associated inflation tube so thatthe valve is in line with an inflation port on the inflation tube topermit delivery of inflation medium.

In FIG. 16, for example, a first one-way valve 300 can be mounted on awall of a first balloon compartment and a second one-way valve 302 canbe mounted on the wall of a second balloon compartment. By thenarranging the two valves in opposite directions along a common axis, aninflation tube 304 having a rotatable inflation port 306 can be disposedbetween the two valves. Then by turning the inflation tube, the firstvalve 300 or the second valve 302 may be selected to deliver inflationmedium through the single inflation tube 304.

Alternatively, as shown in FIG. 17, a first inflation valve 310, asecond inflation valve 312, and a third inflation valve 314, each ofwhich is associated with a respective balloon compartment, may beaxially arranged so that a single inflation tube 316 may be translatedto successfully access each of the one-way valves 310. In this way, eachof the associated balloon compartments may be selectively inflated andreinflated by simply axially translating the inflation tube 316.

As a further alternative, as shown in FIG. 18, a single inflation tube320 having multiple inflation ports 322, 324, and 326 may be disposednext to a linear array of balloon compartments and one-way inflationvalves 330, 332, and 334. In this way, instead of axially translatingthe inflation tube 320, the valves can be selected by rotating the tubeso that only a single inflation port is aligned with a single one-wayvalve at one time.

It will be appreciated that the above-described valve mechanisms andassemblies may be constructed in a wide variety of ways using a widevariety of one-way valve structures. For the purposes of the presentinvention, it is desirable only that the valve structures permitselective introduction of an inflation medium to individual ballooncompartments using a single inflation tube. It will also be appreciatedthat more than one valve may be used in series (not shown) in place of asingle valve to reduce further the potential for leakage of the fillingmedia.

A first specific structure for implementing the inflation assembly ofFIG. 16 is shown in FIG. 19. The inflation tube 304 having inflationport 306 is disposed between a wall 350 of a first balloon and a wall352 of a second balloon. The first one-way valve 300 is positionedthrough the first wall 350, and the second one-way valve 302 ispositioned through the second wall 352. Those valves are shown asduckbill valves. As shown in FIG. 19, the port 306 is aligned with thefirst one-way valve 300 so that introduction of a pressurized inflationmedium through lumen 305 of the inflation tube 304 will open theduckbill valve and allow inflation medium to enter the first balloon. Bythen rotating the inflation tube 350 by 180° so that it is aligned withthe second valve 302, inflation medium can be similarly delivered to thesecond balloon.

A specific valve system constructed generally as shown in FIG. 18 isshown in FIGS. 20, 20A and 20B. The inflation tube 320 is rotatablydisposed within an outer tube 360 which passes between walls 362 and 364of first and second inflatable compartments, respectively. Thedistal-most one-way valve 334 is disposed in a first radial direction onthe outer tube 360, and the next inner one-way valve 332 is offset by90°. The ports 362 and 364 on the inflation tube 320 (FIGS. 20A and 20Bnot illustrated) will be arranged so that in a first rotational positionone port 362 is aligned with one-way valve 332 and in a secondrotational position, a second port 364 is aligned with one-way valve334. At no time, however, is more than one inflation port aligned withmore than one one-way valve on the outer tube 360. Thus, by rotatinginflation tube 320, individual inflatable compartments can be inflated.

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

1. A gastric balloon comprising: a scaffold having a constrainedconfiguration and a deployed, wherein the scaffold can be introducedinto a gastric cavity in the constrained configuration; and at least oneinflatable space-filling compartment secured to the scaffold, saidcompartment assuming a space-filling configuration when inflated atleast partly with a compressible or incompressible fluid.
 2. A gastricballoon as in claim 1, wherein the space-filling compartment(s) have agenerally crescent shape when at least partly inflated with the fluid.3. A gastric balloon as in claim 2, wherein the scaffold is a resilientstructure which conforms to the crescent shape of the space-fillingcompartment when the scaffold is deployed.
 4. A gastric balloon as inclaim 2, wherein the scaffold is an inflatable structure which conformsto the crescent shape of the space-filling compartment when the scaffoldis deployed by inflation.
 5. A gastric balloon as in claim 2, whereinthe scaffold is inflatable with a compressible or an incompressiblefluid.
 6. A gastric balloon as in claim 1, wherein the scaffold forms aplurality of longitudinal channels, and the inflatable space-fillingcompartment(s) is (are) disposed in at least some of the channels, tooccupy at least a portion thereof when inflated.
 7. A gastric balloon asin claim 1, wherein the scaffold has an X-shaped cross-section to definechannels in four quadrants and the inflatable space-filling compartmentincludes at least one section in each of the quadrants.
 8. A gastricballoon as in claim 1, comprising a plurality of separately inflatablespace-filling compartments.
 9. A gastric balloon as in claim 8,comprising at least three separately inflatable space-fillingcompartments.
 10. A gastric balloon as in claim 9, comprising at leastfour separately inflatable space-filling compartments.
 11. A gastricballoon as in claim 1, further comprising at least one inflation tuberemovably connected to the space-filling compartment(s).
 12. A gastricballoon as in claim 11, wherein a separate inflation tube is connectedto each of the space-filling compartments.
 13. A gastric balloon as inclaim 11, wherein a single inflation tube is commonly connected to allof the space-filling compartments.
 14. A gastric balloon as in claim 13,wherein the gastric balloon comprises a plurality of inflatablecompartments, further comprising a valve structure which connects thesingle inflation tube to the plurality of inflatable compartments andwhich permits a user to selectively inflate each inflatable compartment.15. A gastric balloon as in claim 1, further comprising at least oneseparately inflatable external bladder formed over the space-fillingcompartment(s), wherein the bladder shapes the outside of the balloonwhen inflated at least partly with a compressible or incompressiblefluid.
 16. A gastric balloon as in claim 15, further comprising at leastone inflation tube removably connected to the external bladder.
 17. Agastric balloon as in claim 1, further comprising at least one substancedisposed within the wall or interior of at least one of the inflatablespace-filling compartment(s), wherein the substance is detectable uponrelease from the balloon due to breach and secretion, excretion,exhalation, and/or regurgitation by the patient.
 18. A gastric balloonas in claim 11, further comprising a wireless breach detection system,incorporated into a wall of at least one space-filling compartment,wherein said system is adapted to emit a detectable signal if the wallis at least partially breached.
 19. A gastric balloon as in claim 1,wherein at least a portion of the inflatable space-filling compartmentsare coated with or impregnated by an anti-microbial and/oradhesion-resistant agent.
 20. A gastric balloon as in claim 19, whereinall exposed surfaces of the gastric balloon are coated with theagent(s).
 21. An improved gastric balloon of the type having aninflatable chamber, wherein the improvement comprises having a pluralityof inflatable compartments, wherein the compartments have individualvolumes such that the collective volume of the chambers remaininginflated after the deflation of any single chamber is such that theballoon is prevented from passing through the pyloric valve.
 22. Animproved gastric balloon as in claim 21, further comprising a substancedisposed within at least some of the inflatable compartments or walls ofthe inflatable compartments, wherein the substance is detectable uponexcretion, secretion, exhalation, or regurgitation by a patient.
 23. Animproved gastric balloon as in claim 21, further comprising a wirelessbreach detection system incorporated into at least one wall of oneinflatable compartment.
 24. An improved gastric balloon of the typeincluding at least one inflatable space-filling compartment, furthercomprising a self-expanding scaffold which has a size or geometry whichprevents the balloon from passing through the pyloric valve afteraccidental deflation of the inflatable compartments.
 25. An improvedgastric balloon as in claim 24, further comprising a substance disposedwithin at least some of the inflatable compartments or walls of theinflatable compartments, wherein the substance is detectable uponexcretion, secretion, exhalation, or regurgitation by a patient.
 26. Animproved gastric balloon as in claim 24, further comprising a wirelessbreach detection system incorporated into at least one wall of oneinflatable compartment.
 27. An improved gastric balloon of the typecomprising an inflatable compartment having a wall subject to breach,said improvement comprising: a wall formed from at least two layers,wherein each layer has different physical and/or mechanical properties.28. An improved balloon as in claim 27, wherein the properties areselected from the group consisting of stiffness, durability,biocompatibility, chemical resistance, and permeability.
 29. An improvedballoon as in claim 27, further comprising a detectable material presentbetween said layers so that the material is released in the event thewall is breached.
 30. An improved gastric balloon of the type comprisingan inflatable compartment having a wall subject to breach, saidimprovement comprising: a detectable material present in the wall suchthat the material is released if the wall is breached.
 31. An improvedgastric balloon as in claim 30, wherein the detectable material isdispersed within the wall.
 32. An improved gastric balloon as in claim30, wherein the detectable material is disposed between two layers ofthe wall.
 33. An improved gastric balloon of the type comprising aninflatable compartment having a wall subject to breach, said improvementcomprising: a wireless detection system including two probes, whereinthe probes are arranged so that the probes are exposed to stomachcontents only upon breach of the wall; and a transmitter which isconnected to the probes and powered when the probes are exposed tostomach contents.
 34. An improved balloon as in claim 33, wherein atleast one of the probes is a mesh embedded in the wall and the otherprobe is external to the wall.